18.
Your Answer is
Correct Answer is G
Explanation
The loss in this sentence refers to the possible consequences of the phenomenon mentioned above (more than half of the residents left the local area to find work). Therefore, here feel modifies the loss, and an attributive clause (modifying the preceding noun) is used.
Item F/J: Both are adverbial sentences, modifying the subject Santiago, wrong. Note: feel is a sensory verb, and it uses the active form to express the passive, so which felt uses the active form to modify loss.